Siemens Telecommunicazioni S.p.a.

Gte Telecomunicazioni S.p.a.

Antonio Tersalvi

Giampiero Ferraris

A process on a single insulating substrate for depositing in succession a thin layer of tantalium with high resistivity doped with nitrogen and oxygen, a less thin layer of titanium with low resistivity doped with nitrogen, a layer of palladium and a thick layer of gold. Selective chemical attacks of said layers then permit tracing of conducting lines, resistive lines with greater resistance and resistive lines with less resistance.

Process for obtaining passive thin-layer circuits with resistive lines

It is described a process to obtain thin film lines by photolithography of thick resist and subsequent selective galvanic growth of gold which enables to obtain very thin lines (2-10 micron) with high definition, that is with nearly vertical walls and with a tolerance in the width of about 1 micron. Such results have been achieved by using polyimide as thick resist, by particular cure cycles of the same polyimide and by a particular dry etching of the polyimide layer to obtain seats in which afterwards the lines become grown.

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Milan, Italy

Antonio Tersalvi